Process for the manufacture of film-forming solutions



35 known heretofore.

Patented Nov. 5, 1929 are rates KURT RIPPER, OF VIENNA, AUSTRIA,ASSIGNOR TO FRITZ POLLOK, F VIENNA,

AUSTRIA PROCESS FOR THE MANUFACTURE OF FILM-FORMING SOLUTIONS 30Drawing. Original application filed March 20, 1924, Serial No. 700,786,and in Austria March 31, 1923.

Divided andthis application filed June 22, 1925. Serial No. 38,920.

This invention relates to the manufacture of lacquers, films and thelike by condensing urea or its derivatives with formaldehyde.

The present application is a division of my copending application SerialNo. 700,736,

filed March 20, 1924, Patent No. 1,687,312, dated Oct. 8, 1928, for aprocess for manufacturing condensation products. This c0- pendingapplication relates to, the manufacture of condensation products clearas water-' from urea or its derivatives and formaldehyde, the processdescribed therein comprises conducting the first stage of the reactionbetween a urea and formaldehyde, wherein the viscous initial productsare formed in two essential phases, the first in the absence of freehydrogen ions and the second in the presence of free hydrogen ions, byadjusting the C in the first phase, which is completed after applyingheat for a short period of time, to a value of about 10- or below and inthe second phase to a value upwards of 10- but not reaching 10- whereatthe reaction is continued by further heating.

I The symbol C represents usually grammes corresponds to the value p =7,the value C =l0- to the value p =3. This mode of conducting thepolymerization process in an acid medium results in the formation of ahydrophobe emulsion colloid which had been un- If the condensationproduct formed by short heating of the mixture of urea and formaldehydeis'heated for prolongated time or if the concentration of the hydrogenions is increased above a certain 40 limit, this hydrophobe emulsioncolloid is precipitated by cooling the reaction mass afteraccomplishment of the polymerization process. The hydrophobe gelproduced in the above described manner is superior to any other reactionproduct for manufacturing lacquers or films. It was'for the first timethat one succeeded in obtaining lacquers from condensation products ofurea and formaldehyde made with non-aqueous solvents and non-aqueoustempering agents and even with such not mixable with water, by startingfrom the said hydrophobe product. This result is of cause lacquers madewithout such additions have the disadvantage of easily cracking in thewarmth.

Example 30 parts by weight of pure and neutrally reacting urea are mixedwith 100 parts by weight of a 30% aqueous solution of formaldehyde whichis free from acid or is neutralized or is slightly alkaline, the mixturebeing heated to boiling in a boiler with a reflux condenser. After shortboiling 5 parts by weight of boric acid, dissolved in 'a little water,are added thereto; the whole mixture is thereafter further boiled in=theboiler with the reflux condenser for 6 or 7 hours. After being allowedto stand in the cold for several hours, the mass is found to be dividedin two layers, of which the upper one is poured off, whereafter thetough gel forming the lower layer is repeatedly washed with water. Thegel thus produced can be dissolved in non aqueous solvents, such as forinstance epichlorhydrin. Mixed with softening agents this lacquersolution yields a non-cracking coating of lacquer, which is completelyinsensitive to any action of water.

What I claim is: I

1. The process of producing film-forming solutions which consists inreacting on a urea with a solution of formaldehyde by boiling themixture-adjusted to a C not exceeding 10" for a short time, thereafteradjusting the hydrogen ion concentration of the rea'cformed hydrophileemulsion colloid in a hydrophobe colloid on further heating, continuingthe reaction by heatingthe reaction mixture, cooling the reactionproduct whereby the hydrophole colloid is precipitated therefrom,separating the precipitated colloid from the water and dissolving it ina nonaqueous solvent. 7

2. The process of producing film-forming colloid on further heating,continuing the reaction by heating the reaction mixture, cooling thereaction product whereby the hydrophobe colloid is precipitated,separating the precipitated colloid .from the water aiiddissolving it ina nonaqueous solvent.

3. The process of producing film-forming solutions which consists inreacting on a urea with a solution of formaldehyde, the free formic acidcontent of which solution, had been eliminated before starting thereaction, initiating the reaction by boiling the mixture for a shorttime, adjusting the hydrogen ion concentration in the reaction mixtureby 'addition of acid-reacting agents to a value up wards of a C of 10"to cause complete condrophobe colloid is precipitated therefrom,separating the precipitated colloid from the Water, dissolving. it innonaqueous solvents and'addin tempering agents, having the property 0?preventing the films formed by evaporation of the solutions fromcracking.

In testimony whereof I have affixed my signature.

KURT RIPPER.

version of the first formed hydrophile emul sion colloid in a hydrophobecolloid on further heating, continuing the recation by heating thereaction mixture, cooling the reaction product whereby the hydrophobecolloid is precipitated therefrom, separating the precipitatedcolloidfrom the water, and dissolving-it in a nonaqueous solvent.

'4. The process of roducing film-forming solutions which conslsts inreacting on a ura with a solution of formaldehyde, the free 'formic'acid-.content'of which solution hadbeen neutralized before starting thereaction, inltiating the reaction by boiling the mixture for a shorttime, adjusting the ydrogen ion concentration of the reaction mixtureto-a value upwards of a C of IO'T to cause complete conversionof thefirsfilformed hydrophile emulsion colloid in a ydrophobe colloid onfurther heating, continuing the reaction byheating the reaction mixture,cooling the reaction product whereby the hydrophobe' colloid isprecipitated therefrom, separating the precipitated colloid from thewater, dissolving it in anonaqueous solventpand adding a temperingagenti gg- 5. Theprocess ofjproducing film-forming solutions whichconslsts in reacting on a urea with a solution oftformaldehyde, the freefor- Imic acid content of which solution had been neuaralized beforestarting the reaction, initiatin the reaction by boiling the mixture fora s ort' time, adjusting the hydrogen ion concentrationf'in the reactionmixture to a value upwards of a C 'of l0'f'to'cause complete conversionof the first formed hydro- 01d on further heating, continuing the reac-'tion byfurther heating the reaction mixture,

cooling the reaction product whereat the by I i phile emulsioncolloidiin a hydrophobe col-

